Removal of disease such as atherosclerotic plaque, thrombus, and other types of obstructions and partial obstructions from internal body lumens or cavities is a well-established interventional technique. Numerous interventional catheters have been conceived and developed. Most of these systems require placement of a guiding catheter and guide wire prior to introduction and placement of the interventional catheter at the target operating site. Advanceable and/or rotating operating heads have been used to cut and/or ablate obstructions. Many of these prior art systems incorporate aspiration systems to remove the ablated material from the site.
Despite the many and varied approaches to material removal systems, many challenges remain in providing systems for removing material from a lumen, such as a blood vessel, safely and reliably and without causing complications. The safety and reliability of the system is manifestly critical. Recovery of debris generated during a material removal operation, or maceration of the debris to a particle size that will not produce blood vessel damage or embolic events is essential. The flexibility and size of an interventional catheter is also an important feature. The system must be small enough and flexible enough to navigate through sometimes tortuous internal structures and passageways, such as blood vessels, for placement at the target interventional site. The interventional catheter must also have sufficient stiffness and integrity to operate reliably at high rotational rates while allowing for aspiration and/or infusion of fluids to the site.
In interventional catheters that employ a “cutting head,” any cutter structures must be benign during navigation of the operating head to and from the target site, yet effectively remove material during the operation. In addition, cutter structures must effectively remove disease or undesired material without damaging delicate neighboring tissue, such as blood vessel walls or other healthy tissue, which often surrounds the undesired material. Thus, it is important for cutter structures of the interventional catheter to accurately and reliably differentiate between the disease or undesired material and healthy tissue.
The extent and consistency of the disease or undesired material forming an obstruction are frequently not well characterized prior to an intervention. Thus, although interventional catheters and cutter assemblies having different sizes and material removal properties may be provided, and may even be interchangeable on a material removal system, it is difficult to ascertain which combination of features will be most effective in any particular intervention prior to insertion of the device. Various quick-connect systems have been developed to permit removal and installation of multiple operating catheters during a single surgical intervention. This is not ideal, since the interchange, requiring withdrawal and insertion of multiple interventional catheters, is time consuming and increases the risk of the operation. Having access to multiple cutter assemblies having different sizes and different material removal properties on a single interventional operating catheter is highly desirable.
Many prior art interventional catheters are intended to be entirely disposable. That is, the catheter tube, operating head, drive and control mechanisms are provided as sterile, single use, disposable systems. Because such systems have rigorous operating and control requirements, providing an interventional catheter and control assembly as a single-use, disposable system is expensive. It would be desirable to reuse some of the operating and/or control mechanisms without sacrificing sterility and operational convenience.
Several prior art interventional catheters provide for aspiration of liquids and/or debris from the material removal site. In general, such aspiration is provided by a vacuum pump or, in many cases, by an evacuated recovery vessel, such as an evacuated bottle. These systems tend to provide inconsistent and variable vacuum during operation, which reduces the efficiency and effectiveness of the material removal operation and, under certain circumstances, may compromise the health of the patient.
The operation of an advanceable, rotatable operating head is generally under the control of a physician or other professional using some type of a sliding advancement mechanism operated within the sterile field. Advancement of a rotatable operating head to remove undesired material must generally be carefully coordinated with rotational control of the operating head. Rotational speed displays may be provided in the form of an rpm gauge on a control module. Advancement of the operating head is often visualized on a separate display.
Although interventional catheters are used frequently, limitations in the flexibility, reliability and versatility of existing systems limit the types of disease conditions that can be effectively treated. The interventional catheter assemblies and control systems of the present invention have been designed to overcome these limitations.